<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
        "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml" lang="en" xml:lang="en">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<title>Apache Tomcat WebSocket Examples: Multiplayer Snake</title>
<style type="text/css">
#playground {
	width: 640px;
	height: 480px;
	background-color: #000;
}

#console-container {
	float: left;
	margin-left: 15px;
	width: 300px;
}

#console {
	border: 1px solid #CCCCCC;
	border-right-color: #999999;
	border-bottom-color: #999999;
	height: 480px;
	overflow-y: scroll;
	padding-left: 5px;
	padding-right: 5px;
	width: 100%;
}

#console p {
	padding: 0;
	margin: 0;
}
</style>
<script src="https://cdn.jsdelivr.net/sockjs/0.3.4/sockjs.min.js"></script>
</head>
<body>
	<noscript>
		<h2 style="color: #ff0000">Seems your browser doesn't support
			Javascript! Websockets rely on Javascript being enabled. Please
			enable Javascript and reload this page!</h2>
	</noscript>

	<div style="float: left">
		<canvas id="playground" width="640" height="480"></canvas>
	</div>
	<div id="console-container">
		<div id="console"></div>
	</div>
	<script type="text/javascript">
		var Game = {};
		Game.fps = 30;
		Game.socket = null;
		Game.nextFrame = null;
		Game.interval = null;
		Game.direction = 'none';
		Game.gridSize = 10;
		function Snake() {
			this.snakeBody = [];
			this.color = null;
		}
		Snake.prototype.draw = function(context) {
			for ( var id in this.snakeBody) {
				context.fillStyle = this.color;
				context.fillRect(this.snakeBody[id].x, this.snakeBody[id].y,
						Game.gridSize, Game.gridSize);
			}
		};
		Game.initialize = function() {
			this.entities = [];
			canvas = document.getElementById('playground');
			if (!canvas.getContext) {
				Console.log('Error: 2d canvas not supported by this browser.');
				return;
			}
			this.context = canvas.getContext('2d');
			window.addEventListener('keydown', function(e) {
				var code = e.keyCode;
				if (code > 36 && code < 41) {
					switch (code) {
					case 37:
						if (Game.direction != 'east')
							Game.setDirection('west');
						break;
					case 38:
						if (Game.direction != 'south')
							Game.setDirection('north');
						break;
					case 39:
						if (Game.direction != 'west')
							Game.setDirection('east');
						break;
					case 40:
						if (Game.direction != 'north')
							Game.setDirection('south');
						break;
					}
				}
			}, false);
			Game.connect();
		};
		Game.setDirection = function(direction) {
			Game.direction = direction;
			Game.socket.send(direction);
			Console.log('Sent: Direction ' + direction);
		};
		Game.startGameLoop = function() {
			if (window.webkitRequestAnimationFrame) {
				Game.nextFrame = function() {
					webkitRequestAnimationFrame(Game.run);
				};
			} else if (window.mozRequestAnimationFrame) {
				Game.nextFrame = function() {
					mozRequestAnimationFrame(Game.run);
				};
			} else {
				Game.interval = setInterval(Game.run, 1000 / Game.fps);
			}
			if (Game.nextFrame != null) {
				Game.nextFrame();
			}
		};
		Game.stopGameLoop = function() {
			Game.nextFrame = null;
			if (Game.interval != null) {
				clearInterval(Game.interval);
			}
		};
		Game.draw = function() {
			this.context.clearRect(0, 0, 640, 480);
			for ( var id in this.entities) {
				this.entities[id].draw(this.context);
			}
		};
		Game.addSnake = function(id, color) {
			Game.entities[id] = new Snake();
			Game.entities[id].color = color;
		};
		Game.updateSnake = function(id, snakeBody) {
			if (typeof Game.entities[id] != "undefined") {
				Game.entities[id].snakeBody = snakeBody;
			}
		};
		Game.removeSnake = function(id) {
			Game.entities[id] = null;
			// Force GC.
			delete Game.entities[id];
		};
		Game.run = (function() {
			var skipTicks = 1000 / Game.fps, nextGameTick = (new Date)
					.getTime();
			return function() {
				while ((new Date).getTime() > nextGameTick) {
					nextGameTick += skipTicks;
				}
				Game.draw();
				if (Game.nextFrame != null) {
					Game.nextFrame();
				}
			};
		})();
		Game.connect = (function() {
			Game.socket = new SockJS("/snake");
			Game.socket.onopen = function() {
				// Socket open.. start the game loop.
				Console.log('Info: WebSocket connection opened.');
				Console.log('Info: Press an arrow key to begin.');
				Game.startGameLoop();
				setInterval(function() {
					// Prevent server read timeout.
					Game.socket.send('ping');
				}, 5000);
			};
			Game.socket.onclose = function() {
				Console.log('Info: WebSocket closed.');
				Game.stopGameLoop();
			};
			Game.socket.onmessage = function(message) {
				// _Potential_ security hole, consider using json lib to parse data in production.
				var packet = eval('(' + message.data + ')');
				switch (packet.type) {
				case 'update':
					for (var i = 0; i < packet.data.length; i++) {
						Game
								.updateSnake(packet.data[i].id,
										packet.data[i].body);
					}
					break;
				case 'join':
					for (var j = 0; j < packet.data.length; j++) {
						Game.addSnake(packet.data[j].id, packet.data[j].color);
					}
					break;
				case 'leave':
					Game.removeSnake(packet.id);
					break;
				case 'dead':
					Console.log('Info: Your snake is dead, bad luck!');
					Game.direction = 'none';
					break;
				case 'kill':
					Console.log('Info: Head shot!');
					break;
				}
			};
		});
		var Console = {};
		Console.log = (function(message) {
			var console = document.getElementById('console');
			var p = document.createElement('p');
			p.style.wordWrap = 'break-word';
			p.innerHTML = message;
			console.appendChild(p);
			while (console.childNodes.length > 25) {
				console.removeChild(console.firstChild);
			}
			console.scrollTop = console.scrollHeight;
		});
		Game.initialize();
	</script>
</body>
</html>